In a multiethnic urban population in which a low percentage of individuals meet dietary guidelines, the sodium to potassium intake ratio (Na:K) was shown to be an independent predictor of stroke risk, according to the results of the Northern Manhattan Study (NOMAS) published in Stroke.
Stroke-free participants from NOMAS — a population-based, cohort study of stroke incidence — were followed for incident stroke. Dietary data from food frequency questionnaires were evaluated with respect to intake of Na and K. Multivariable Cox proportional hazard models were utilized to estimate hazard ratios (HR).
A total of 2496 participants with no history of myocardial infarction at baseline had dietary data available from the food frequency questionnaire. Mean patient age was 69±10; approximately 64% of the cohort were women; 55% were Hispanic, 24% black, and 21% white. Mean dietary Na intake in the participants was high (3057±1510 mg/d); only a small percentage of the population had Na intake levels below dietary guidelines (<2300 mg/d, 36%; <1500 mg/d, 12%). Mean dietary K intake was low (2591±1099 mg/d), and only a small percentage of individuals met K intake guidelines (>4700 mg/d, 5%). The mean Na:K ratio in the cohort was 1.22±0.43, and 38% of the participants had both high Na and K intake.
All participants were followed for a mean of 12±5 years; a total of 268 strokes were reported in the cohort (227 ischemic) over this period. A higher Na:K ratio was associated with a significantly increased risk for ischemic stroke and for all strokes (HR 1.6; 95% CI, 1.2-2.1). The investigators noted that in this multiethnic population, increasing K intake could help to offset the risk for stroke associated with high Na intake.
The findings of this study highlight the importance of considering dietary intake as a whole, rather than examining micronutrients on an individual basis. Additional research is warranted to elucidate the combined effect of Na and K on risk of stroke.
Willey J, Gardener H, Cespedes S, Cheung YK, Sacco RL, Elkind MSV. Dietary sodium to potassium ratio and risk of stroke in a multiethnic urban population: the Northern Manhattan Study. Stroke. 2017;48(11):2979-2983.